When you lose weight, BMR/RMR goes down. Some of this is simply due to reduced body weight (a smaller body burns less calories) but there is also an adaptive component due to changes in hormones like leptin, insulin, nervous system output and thyroid hormones (this topic is discussed in detail in both The Rapid Fat Loss Handbook and A Guide to Flexible Dieting). This lessens the actual deficit that is being created because the previously estimated maintenance value is no longer correct (to keep losing fat at anywhere near the same rate, calories have to be reduced further to take this reduction into account).

The Thermic effect of food is related directly to the amount of food that you’re eating. Now, TEF is usually rough-estimated at 10% of total food intake (this is just an average value for average diets). But that means that if you reduce food intake by 500 cal/day, you will be burning 50 cal/day less via TEF. Your previous maintenance of 2500 has already been reduced to 2450 cal/day. So the assumption of a static 2500 cal/day maintenance is already made invalid simply by the act of reducing food intake (albeit slightly).

Ok, you say, what if I add exercise instead? Well, some research has found that (and this usually happens in older people) excessive amounts of activity burned during exercise causes people to move around less later in the day. For example, say you put yourself through 500 calories of hard activity but, due to fatigue, you sit on the couch more later that night, burning 300 calories less than you expended before training. The supposed 500 calorie deficit you’re creating is really only 200 calories because your SPA/NEAT has adjusted itself. You might expect one pound per week fat loss but the deficit is actually less than half of that (200 cal/day * 7 days = 1,400 calories = 0.4 pounds fat per week).

As well, people often get lethargic on a diet, they move around less. The 2500 cal/day maintenance level goes down because SPA/NEAT goes down because they have less energy. The amount of daily movement that occurred at caloric balance (or surplus) drops. So the expected deficit (and hence change in body mass) is no longer accurate since parts of the energy out equation have changed.

I’d note that all of this goes for weight gain and overeating as well. All of the components can change, sometimes considerably. So the predicted or expected weight gain in response to a given change in energy intake is rarely exactly what is seen. That’s in addition to water balance issues and the difference in caloric value of muscle and fat.

BMR/RMR goes up a bit when people overeat, of course gaining weight raises RMR/BMR because a larger body burns more calories. Since TEF is directly related to energy intake, if you increase food intake, TEF goes up slightly (and this depends on the nutrient in question with protein having the largest effect).

Changes in SPA/NEAT can vary hugely and explain most of the discrepancies in expected vs. actual weight gain. In the earliest study, when overfed nearly 1000 calories/day weight/fat gain varied almost 10 fold but this was explained by massive variance in NEAT; some people increased their spontaneous movement by 700 cal/day (making the true surplus 300 cal/day) while one poor person (a woman) had her NEAT go down a little bit (she gained the most fat). This is mostly genetic, unfortunately.

The point of all of this is this: When people say that the energy balance equation is invalid, this is simply not the case. The equation is completely valid, what is invalid are the assumptions that people are making about what the equation means or says.

Summing Up

I think when you read articles decrying the energy balance equation as invalid or incorrect, you’ll find that they ignore (or simply are unaware) of all of the above. The equation is perfectly valid and humans are as subject to the laws of thermodynamics as anything else in the universe. Physics is not just a good idea, kids, it’s the law.

Most claims that the energy balance equation is invalid are due to people simply not knowing what they are talking about. The equation is valid, it has to be, what’s invalid are people’s assumptions about how things should work.

That's interesting. We know that nutrient deficiency creates constant hunger which leads to overeating. It seems to me that nutrient density would be highly important to satiation which would be highly important to proper calorie regulation.

Low nutrient diets and foods that lack satiety lead to increased caloric consumption, which leads to weight gain. Again, CICO. This is nothing new, and one of the fundamentals of CICO and why Primal works - whole foods contain more nutrition and satiety per calorie. That's all this is.

Originally Posted by The Rebooted Body

That's not the CICO argument, buddy. The CICO argument is that it's ONLY about the calories. You can't then go on to say that nutrient density helps people eat less because they're not starving all the time. The very FACT that people can't follow CICO UNLESS they worry about food quality is what disproves the theory of CICO and PROVES the theory of the importance of hormone regulation and micronutrient density OVER calorie quantity.

See above. That is EXACTLY what you said - low satiety foods lead to more calorie consumption which leads to more weight gain. That is the perfect definition of CICO. Thanks for agreeing buddy.

Don't put your trust in anyone on this forum, including me. You are the key to your own success.

Low nutrient diets and foods that lack satiety lead to increased caloric consumption, which leads to weight gain. Again, CICO. This is nothing new, and one of the fundamentals of CICO and why Primal works - whole foods contain more nutrition and satiety per calorie. That's all this is.

Just want to point out that this is CICO AND quality of food, not just CICO on its own.

Just want to point out that this is CICO AND quality of food, not just CICO on its own.

No, it's CICO. All CICO says is you must consume more calories than you expend to gain weight and consume less calories than you expend to lose weight. It has absolutely nothing to do with nutrient quality. Never has, never will. All that's needed to lose weight is an energy deficit.

Don't put your trust in anyone on this forum, including me. You are the key to your own success.

Here we have two people who both eat junk food, however one overconsumes it and thus, is obese. Then we have the little weedy dude who sometimes has a couple of chocolate bars for breakfast, burritos for lunch and pasta for dinner but, well, is skin and bones. All because he undereats, and she overeats. No "insulin' factor, no good quality food, just over/under consumption and it's results.

No, it's CICO. All CICO says is you must consume more calories than you expend to gain weight and consume less calories than you expend to lose weight. It has absolutely nothing to do with nutrient quality. Never has, never will. All that's needed to lose weight is an energy deficit.

Fair enough. CICO can be a basis, but it isn't nearly close to what the means is to get to the end.

My sister managed to lose about 15 lbs eating mostly processed food. She's 25, 5'8", weighs about 130 lbs now. She maintains on about 1200 calories per day. You can lose weight no matter what you eat, as long as you don't overeat!

Now, health is another issue. She gets the flu every few months and her wounds take a long time to heal. She also gains weight very easily.

My sister managed to lose about 15 lbs eating mostly processed food. She's 25, 5'8", weighs about 130 lbs now. She maintains on about 1200 calories per day. You can lose weight no matter what you eat, as long as you don't overeat!

Now, health is another issue. She gets the flu every few months and her wounds take a long time to heal. She also gains weight very easily.

Sounds about right. She's probably severely nutrient deficient and therefore has a weak immune system, and her low-nutrient starvation diet is so crushing on her metabolic rate that any momentary calorie increase yields fast weight gain, likely mostly fat. But that's CICO, 100%. All energy balance. If she ate real food, increased her calories and became nutritionally replete, she'd probably raise her metabolic rate and be able to maintain on more calories. You should give her a copy of The Primal Blueprint for her birthday

Don't put your trust in anyone on this forum, including me. You are the key to your own success.

Sounds about right. She's probably severely nutrient deficient and therefore has a weak immune system, and her low-nutrient starvation diet is so crushing on her metabolic rate that any momentary calorie increase yields fast weight gain, likely mostly fat. But that's CICO, 100%. All energy balance. If she ate real food, increased her calories and became nutritionally replete, she'd probably raise her metabolic rate and be able to maintain on more calories. You should give her a copy of The Primal Blueprint for her birthday

She's not interested at all in improving her health. She just wants to stay as thin as possible whilst eating what she likes (mainly desserts and sweets). She used to exercise to lose weight, but didn't work for her, and she gave that up, now just controls food intake. Her resting heart rate is only 40/min, which concerned her doctor, but they couldn't find any reason for it. Young bodies can take a lot of abuse before the person feels compelled to make changes.